The present invention relates in general to chain conveyors and in particular to a scraper chain conveyor of the type which has an elongated trough supporting at its central part a conveying chain, particularly a double chain assembled of vertical ring-shaped and horizontal disc-shaped chain elements and including scraping members secured to the chain at a space from one another or being formed as a chain link, the scrapers extending transversely across the conveyor path and being driven together with the chain in the longitudinal direction of the trough by means of a sprocket wheel energized by driving means arranged at least at one end of the conveyor.
Conventional scraper chain conveyors of this type used for example in mining have the disadvantage that stresses acting on the chain increase more than proportionally with the increase of the conveyor length. The reason for the disproportional increase of stresses is the additional friction resulting from misalignment of respective sections of the conveyor trough which is unavoidable during the practical operation and which increases similarly as in the case of a looping friction exponentially with the sum of individual deviations. An additional disadvantage of prior art conveyors of this type is the fact that when a conveying double chain is employed, it can be operated along a curve only to a very limited degree or not at all and additional devices are necessary to extend the conveyor along a curve.
Moreover the known scraper chain conveyors have the disadvantage that an excessive prestressing of the conveying chain is necessary in order to insure a disturbance free operation. The prestressing here is especially required for the conveyor having conveying chains arranged at their central plane inasmuch as apart from controlling the suspended chain at the terminal drives it is also necessary to prestress the chain for adjusting the position of the scraping iron pieces (side attachments) above their vertical central axes.